Merritt Butrick (T'Jon) and Judson Scott (Sobi) both appeared in Star Trek II: The Wrath of Khan (1982) as, respectively, Kirk's son David and Khan's right hand man, Joachim.
One of Merritt Butrick's final appearances before his death. His only other form of an "appearance" would be in Star Trek VI: The Undiscovered Country (1991) when Kirk is looking at his photograph.
The visual effect of the fluctuating force field around the Enterprise-D while near the star Delos was created by using a bowling ball which was trickled with salt. The salt bumping off the bowling ball was used and squeezed during the digital composition and turned upside down to give this effect.
The makeup of the Ornarans would serve as the basis for the makeup of the Bajorans starting in Ensign Ro (1991), before being streamlined on Star Trek: Deep Space Nine (1993).
The episode was an indictment of illegal drug addiction, especially given the country's mood at the time with President Ronald Reagan's anti-drug efforts in full swing and other programs like the DARE program becoming prominent in schools. The episode was also almost prophetic in that some drug cartels evolved a corporate structure and acted more like businessmen than criminals at the expense of drug users.